the entire Beiping area was effectively under Yan control. As the Yan forces captured Huailai, the Prince of Gu fled to Nanjing from his territory in Xuanfu, which was situated near the Yan forces. In August, an imperial order demanded that the Princes of Liao and Ning return to Nanjing. The Prince of Liao accepted the order while the Prince of Ning rejected it. The Prince of Dai intended to support the Yan forces, but was forced to remain under house arrest in Datong. Government response, 1399–1400 First offensive In July 1399, news of the rebellion had arrived in Nanjing. The Jianwen Emperor ordered the removal of royal status from the Prince of Yan and began to assemble an attack on Yan forces. A headquarters for the expedition was set up in Zhending, Hebei province. Since many of the generals in the Ming court had either died or been purged by the Ming founder Zhu Yuanzhang, the lack of experienced military commanders was a major concern. With no other options, the 65-year-old Geng Bingwen was appointed as the commander and led 130,000 government forces north on an expedition against the Yan forces. On 13 August, the government forces arrived in Zhending. To prepare for the offensive, the forces were divided and stationed in Hejian, Zhengzhou and Xiongxian separately. However, on 15 August, the Yan forces assaulted Xiongxian and Zhengzhou by surprise and captured both of the cities also annexing their forces. One of the generals in Geng Bingwen's camp surrendered to Zhu Di and informed him of the positions of Geng Bingwen forces. Zhu Di instructed the general to return the message that the Yan forces were approaching soon, to convince Geng Bingwen to gather his forces together to prepare for the general attack. On 24 August, the Yan forces arrived in Wujixian. Based on the information gathered from the locals and the surrendered troops, they began to prepare to raid the government forces. The Yan forces launched a surprise raid on Geng Bingwen the next day, and a full-scale battle ensued. Zhu Di personally led a strike force against the flank of government forces, and Geng Bingwen suffered a crushing defeat as a result. Over 3,000 men surrendered to the Yan forces, and the remainder of the government forces fled back to Zhending. General Gu Cheng surrendered to Zhu Di. For the next several days, the Yan forces attempted